1. Field of the Invention
The present invention relates to explosives disruptors for remote disruption of explosive devices such as pipe bombs, letter bombs, hand grenades, land mines, etc., and, more particularly, to a new recoil reduction adapter attachable between barrel and breech of a conventional explosives disruptor for venturi-venting of combustion gases in order to substantially eliminate recoil which might otherwise endanger people or equipment in the vicinity of the disrupter.
2. Description of the Background
Emergency service personnel responsible for explosive device disposal are often called upon to render explosive devices safe, such as pipe bombs, letter bombs, hand grenades, land mines, etc. The task of disarming such devices is often accomplished by a robot carrying some form of de-arming device or remote disruption. FIG. 1A is a perspective photo of a robotic disposal unit carrying a forwardly-wielded robotic arm as well as a prior art explosives disruptor 2 for firing a projectile.
Bomb squads typically use a variety of disruptors, which are shotgun-like tubes capable of shooting air, water, shot or slugs at the target. These are used to incapacitate many types of explosives, and are particularly effective in removing the ends of pipe bombs.
By way of example, Cherry, U.S. Pat. No. 4,957,027 discloses a multi-barrel de-armer that requires a shock tube to fire a small arms cartridge into an explosive device.
Heller, U.S. Pat. No. 5,210,368 discloses a tripod-mounted, electrically activated de-armer that fires a shotgun shell at an explosive device.
Gilbert, U.S. Pat. No. 5,515,767 discloses a recoil-absorbing de-armer which fires a projectile from a barrel by means of an explosive charge placed behind the projectile.
The most typical explosives disrupters operate by firing a solid projectile or water at an explosive device so as to disrupt the fuse mechanism of the explosive device, ideally without detonating the explosive device. These explosives disrupters comprise a barrel with attached breech, the barrel containing an explosive (shotgun shell) charge which, when initiated, propels shot towards the target. Although these explosives disrupters are operated by remote control, problems can still arise from the mechanical reaction caused by firing the projectile(s). The barrel can recoil with a momentum sufficient to endanger people or equipment in the vicinity of the disrupter.
Consequently, for any explosives disrupter that fires a shotgun shell at an explosive device, there is a need for improved recoil reduction.
In this regard, U.S. Pat. No. 6,644,166 to Alexander et al. issued Nov. 11, 2003, shows an explosives disrupter with a flexible, recoil-absorbing system for minimizing the effects of recoil on the accuracy of the device.
U.S. Pat. No. 5,515,767 to Gilbert issued May 14, 1996 shows a de-arming device with a sleeve surrounding the barrel, so as to define an annular chamber accommodating solid or liquid recoil absorbing material. Radial ports interconnect the barrel and the annular chamber so that when the projectile is fired the annular chamber is pressurized and the recoil absorbing material is expelled rearward from the chamber, so as to counteract recoil.
In both of the foregoing devices the recoil reduction is accomplished with fairly complex equipment and liquids. Due to their level of complexity, these recoil reduction mechanisms are an integral part of the disrupter and cannot be retrofit to an existing disrupter. Moreover, such complex hydraulics, springs, shock absorbers, etc., are expensive, difficult to use, and of such modest effectiveness (50–70% reduction in recoil) that emergency squads that buy them eventually wind up not using them.
It would be far more advantageous to provide a pneumatic recoil reduction adapter that is simple in design, inexpensive to manufacture, convenient to use, that can be retrofit to any disrupter, and which yields an 80–90% reduction in recoil.
For purposes of illustration, FIG. 1B is a perspective side photo of a prior art disrupter 2 without recoil reduction. The disrupter 2 generally includes a disrupter barrel 10 coupled to a breech portion 30. The disrupter barrel 10 is an elongate rod having a coupling at one end, preferably a screw coupling, for attachment to breech portion 30. Internally, the disrupter barrel is open at the loading end where it attaches to breech portion 30 for insertion of a shot cartridge, and has a smooth bore throughout for ejecting the shot. Barrel 10 may be any commercially available projectile-firing disrupter, such as a PAN (Percussion Actuated Non-electric) disrupter, distributed by Ideal Products, Lexington, Ky. under the trademark PAN DISRUPTER™. Typically, the midsection of disrupter barrel 10 is attached to a support frame or robotic device (as in FIG. 1). The breech portion 30 is a machined component formed with a coupling at one end, such as internal screw-threads, for screw-insertion onto the disrupter barrel 10. There are a variety of commercially-available breeches most often sold in combination with a particular disrupter barrel 10, such as the PAN disrupter identified above (this breech is also shown in the Cherry '027 patent). In operation, the breech 30 is unscrewed from the disrupter barrel 10, and a cartridge such as a standard or modified shotgun shell is inserted into the loading end of the barrel 10. The breech 30 is then screwed back onto disrupter barrel 10. The breech portion 30 includes a firing mechanism for firing the cartridge (not shown), which is typically activated by coupling a pneumatic system (known as a “shock tube” to nipple 37. A blast of air through the shock tube drives the firing mechanism into the cartridge, which is then propelled the entire length of the barrel 10.